Of the 18.9 million annual deaths (1997) due to infectious diseases, about 7.5 million, in addition to significant morbidity, are the result of infections by Salmonella typhi, S. paratyphi A, hepatitis B virus (HBV), Plasmodium falciparum, Streptococcus pneumoniae and Mycobacterium tuberculosis. In the belief that improving health, nutrition and economic well-being (the later dependant on the first two) provides the best means to enhance the quality of life globally and thus reduces conditions that result in warlike and terrorist behavior, we propose a vaccine development program based on our recent technical developments in using recombinant attenuated Salmonella vaccines. Our objectives include: (a) to design, construct and evaluate an attenuated derivative of S. paratyphi A that will serve as an antigen delivery vector by exhibiting regulated delayed lysis within effector lymphoid tissues in the immunized individual to release hepatitis B virus (HBV) core particles encoding (i) HBV pre $1, pre $2 and T-cell epitopes as a preventative/therapeutic vaccine against HBV and (ii) P. falciparum circumsporozoite epitopes as a vaccine against malaria; (b) to construct and evaluate the contribution of strain background and the RpoS* phenotype on immunogenicity of a recombinant antigen expressed by attenuated S. typhi vaccine strains; and (c) to design, construct and evaluate recombinant attenuated S. typhi vaccines to express and deliver protective antigens specified by genetic information from (i) S. pneumoniae to prevent pneumococcal disease caused by strains with diverse capsular serotypes and (ii) M. tuberculosis as a preventative/therapeutic vaccine. The S. paratyphi A and S. typhi recombinant vaccines should also provide immunity to infection by S. paratyphi A and S. typhL We will also develop our Master File, prepare and fully characterize candidate vaccine Master Seeds for stability and safety, prepare and submit protocols for IRB approvals, submit information necessary to obtain INDs, and perform any other work needed to arrange that the best candidate vaccines be clinically evaluated in human volunteers.